Abstract

A physical meaning of the higher-order Landau mode is proposed from the theoretical calculation of the dispersion relation. When the plasma is composed of two electron temperatures, the dispersion relation of the two-temperature mode (the modified fundamental Landau mode) suddenly merges into one of the next higher-order Landau modes in the region ω⁄ωp<1 (ωp: electron plasma frequency) as the temperature of the small high energy tail in the velocity distribution increases.